1. Technical Field
This invention relates to base oils suitable for use in lubricants of enhanced performance and also to a process for the production of such a base oil using a specified set of reaction conditions.
2. Prior Art
As a result of technical innovations in an industrial sector of machinery, there have recently aroused sophisticated automotive engines, compact hydraulic equipment for use at high pressure and with high precision compressors apparatus of high performance and economy size and various other machine tools of good machinability. To cope with this trend, lubricating oils are literally required which are sufficient in service life even under adverse conditions, economical in energy and free from environmental pollution. Several base oils for lubricants of the character mentioned are known in common use.
Prior methods of base oil production as by solvent refining are rather dependent upon a limited grade of starting oil of good quality and hence high cost because oil fractions are generally variable or irregular in nature with their sources of supply. In an effort to solve this problem an advanced method has been proposed in which starting oils can be used from a diversified source of supply. Such method involves hydrocracking a given oil fraction and thereafter subjecting the thus treated oil to hydrofinishing, both steps at elevated pressure. The resulting base oil is acceptable in regard to great viscosity and small pour point.
The above hydrocracking method, however, has a drawback in that it needs a reaction pressure as high as 200 kg/cm.sup.2, meaning large plant investment. Furthermore, the resultant base oil is objectionably rich in polycyclic naphthenes which are liable to cause malfunction and conversely poor in alkylbenzenes which are desirable as serving to dissolve sludge which would generate from any additive in the ultimate lubricant or from that lubricant per se.